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Physics and Astronomy

Physics & Astronomy Colloquium

3:30 PM, Friday, April 24, 2015
Room 155, Chem-Phys Building

Dr. Douglas Natelson
Rice University

Heating in atomic- and molecular-scale junctions

When a battery is connected to a wire, the macroscopic electrochemical energy of the battery eventually and irreversibly winds up as heat, the disorganized motions of the (very) many microscopic degrees of freedom of the electrons and ion cores of the conductor. This happens through the electron-vibrational coupling (transferring energy to the motions of ions) and electron-electron interactions (broadening the electronic distribution function). When the conductor approaches atomic dimensions, and we are now discussing an open quantum system with a small number of degrees of freedom driven out of equilibrium, the situation is tricky. While many theoretical analyses of these processes have been performed in various limits, historically it has been very difficult experimentally to interrogate the microscopic degrees of freedom on the nanometer length scales required for quantitative local understanding. I will present measurements of Raman response in biased single-molecule junctions, where the Raman response probes both vibrational populations and the electronic continuum. I will also present measurements of shot noise in biased atomic-scale metal junctions and will discuss this data in the context of vibrational and electron-electron interactions. These approaches let us see where energy is flowing and give us insights into sources of dissipation.

Refreshments will be served in CP 179 at 3:15 PM